JP7230401B2 - TRANSMISSION SYSTEM, TRANSMISSION DEVICE, AND TRANSMISSION METHOD - Google Patents

Description

The present invention relates to a transmission system, a transmission device, and a transmission method.

For example, when a supervisory signal light of a transmission system is multiplexed with a main signal light obtained by wavelength-multiplexing a plurality of wavelengths of light, so that the supervisory signal light is reliably received by the optical transmission device on the receiving side. A transmission device on the transmission side is provided with an amplifier for supervisory signal light that is independent of an amplifier for main signal light (see, for example, Patent Document 1).

JP 2009-159290 A

In the above case, if the transmission power of the supervisory signal light increases due to amplification, nonlinear optical effects such as cross-phase modulation may occur between the main signal light and the supervisory signal light in the transmission line, and the transmission quality of the main signal light may deteriorate. There is On the other hand, if the power of the supervisory signal light is reduced, the nonlinear optical effect can be suppressed. There is a risk of

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a transmission system, a transmission apparatus, and a transmission method capable of suppressing the nonlinear optical effect without deteriorating the monitoring control function.

In one aspect, a transmission system includes a first transmission device that transmits main signal light to a transmission line, and a second transmission device that receives the main signal light from the first transmission device via the transmission line. and the first transmission device includes an output unit for outputting supervisory signal light containing information on supervisory control of the first transmission device and the second transmission device, an attenuation unit for attenuating the supervisory signal light, and the supervisory signal light. The second transmission device has a multiplexing unit that multiplexes the signal light with the main signal light, and a control unit that controls the attenuation amount of the attenuation unit. and a demultiplexer for demultiplexing the supervisory signal light, a first detector for detecting power of the supervisory signal light, a receiver for receiving the supervisory signal light, and the monitor detected by the first detector. a notification unit that notifies the first transmission device of the power of the signal light, and the control unit is defined in the specifications of the power of the supervisory signal light notified from the notification unit and the light reception characteristics of the reception unit. by controlling the attenuation of the attenuator so that the power of the supervisory signal light notified from the notification unit approaches the minimum light sensitivity when the difference from the minimum light sensitivity is greater than a first threshold, The power of the supervisory signal light is reduced to suppress nonlinear optical effects of the main signal light and the supervisory signal light in the transmission line without degrading the supervisory control functions of the first transmission device and the second transmission device. do .

In one aspect, a transmission apparatus transmits a main signal light to another transmission apparatus via a transmission line, and transmits supervisory signal light including information on supervisory control of the transmission apparatus and the other transmission apparatus. an output unit for outputting, an attenuating unit for attenuating the supervisory signal light, a combining unit for combining the supervisory signal light with the main signal light, and the supervisory signal light received by the receiving unit of the other transmission device and the minimum photosensitivity defined in the specifications of the photodetection characteristics of the receiver unit is greater than a first threshold, the power of the supervisory signal light received by the receiver unit approaches the minimum photosensitivity. by controlling the attenuation of the attenuator, the power of the supervisory signal light is reduced, and the main signal light in the transmission path is maintained without lowering the supervisory control functions of the transmission device and the other transmission device. and a controller for suppressing the nonlinear optical effect of the supervisory signal light .

In one aspect, the transmission method is a transmission method for transmitting main signal light from a first transmission device to a second transmission device via a transmission line, wherein the first transmission device comprises the first transmission device and the second transmission device. The second transmission device outputs supervisory signal light containing information about supervisory control of a transmission device, attenuates the supervisory signal light by an attenuator, multiplexes the supervisory signal light with the main signal light, and demultiplexing the main signal light and the supervisory signal light input from a path, detecting the power of the supervisory signal light by a first detector, receiving the supervisory signal light by a receiver, and notifies the first transmission device of the power of the supervisory signal light detected by the first transmission device, and the first transmission device receives the power of the supervisory signal light notified from the second transmission device and the light reception characteristic of the receiver. when the difference from the minimum light sensitivity specified in the specifications is greater than a first threshold, the attenuation of the attenuator is adjusted so that the power of the supervisory signal light notified from the second transmission device approaches the minimum light sensitivity. By controlling, the power of the supervisory signal light is reduced, and the power of the main signal light and the supervisory signal light in the transmission line is reduced without lowering the supervisory control functions of the first transmission device and the second transmission device. This is a method of suppressing nonlinear optical effects .

As one aspect, nonlinear optical effects can be suppressed without degrading the monitoring control function of the transmission device.

1 is a configuration diagram showing a transmission system of a first embodiment; FIG. 3 is a flow chart showing an example of supervisory signal light processing in a transmission device on the receiving side; 4 is a flow chart showing an example of processing for transmitting supervisory signal light in a transmission device on the transmission side; 7 is a flowchart illustrating an example of attenuation control processing in a transmission device on the transmission side; FIG. 11 is a configuration diagram showing a transmission system of a second embodiment; 3 is a flow chart showing an example of processing of supervisory signal light and main signal light in a transmission device on the receiving side; 5 is a flow chart showing an example of transmission processing of supervisory signal light and main signal light in a transmitting-side transmission device; FIG. 11 is a flowchart showing another example of attenuation amount control processing in the transmission device on the transmission side; FIG.

(First embodiment)
FIG. 1 is a block diagram showing the transmission system of the first embodiment. The transmission system has a set of transmission devices 1a, 1b connected via transmission lines 90, 91 such as optical fibers.

The transmission devices 1a and 1b are, for example, wavelength multiplexing transmission devices such as ROADMs (Reconfigurable Optical Add-and-Drop Multiplexers). The transmission apparatuses 1a and 1b transmit main signal lights Sm and Sm' obtained by wavelength-multiplexing a plurality of wavelength lights with different wavelengths to the other transmission apparatuses 1b and 1a. In the example described later, a process of transmitting the main signal light Sm from the transmission device 1a to the transmission device 1b via the transmission line 90 will be described. Transmission processing is also performed in the same manner.

The transmission device 1 a is an example of a first transmission device and transmits main signal light Sm to the transmission line 90 . The main signal light Sm is wavelength-multiplexed with a plurality of wavelength lights including user data such as Ethernet (registered trademark, hereinafter the same) frames. The transmission device 1b is an example of a second transmission device, and receives the main signal light Sm' from the transmission device 1a via the transmission line 90. FIG. Reference Ra indicates the path of the main signal light Sm transmitted from the transmission device 1a to the transmission device 1b, and reference Rd indicates the route of the main signal light Sm' transmitted from the transmission device 1b to the transmission device 1a.

In addition, the transmission devices 1a and 1b combine the supervisory signal light Sc containing information (alarms, etc., hereinafter referred to as "supervisory control information") regarding the supervisory control of the transmission devices 1a and 1b into the main signal lights Sm and Sm'. and transmits it to the other transmission device 1b, 1a. The supervisory signal lights Sc and Sc' have wavelengths separated by a predetermined wavelength band from the wavelength band of the wavelength light included in the main signal lights Sm and Sm'. Symbol Rb indicates the path of supervisory signal light Sc transmitted from transmission device 1a to transmission device 1b, and symbol Rc indicates the route of supervisory signal light Sc' transmitted from transmission device 1b to transmission device 1a.

If the transmission power of the supervisory signal light Sc is too strong, the main signal light Sm and the supervisory signal light Sc may undergo nonlinear optical effects such as cross-phase modulation in the transmission path 90, resulting in deterioration of the transmission quality of the main signal light Sm. There is

Therefore, the transmission device 1a controls the attenuation of the VOA 21a so that the power of the supervisory signal light Sc received by the other transmission device 1b approaches a predetermined target value. Therefore, by appropriately setting the target value, the transmission device 1a can reduce the transmission power of the supervisory signal light Sc while satisfying the transmission quality requirements of the supervisory signal light Sc. Therefore, the transmission device 1a can suppress the nonlinear optical effect without deteriorating the monitoring control function. The configuration of the transmission devices 1a and 1b will be described below.

The transmission device 1a includes an FPGA (Field Programmable Gate Array) 10a, a memory 12a, an SFP (Small Form-factor Pluggable) 20a, optical amplifiers 30a and 31a, a variable optical attenuator (VOA) 21a, 32a. The transmission device 1a further includes optical splitters 22a, 23a, filters 33a, 34a, and PDs (Photo Diodes) 24a, 25a. The transmission device 1b, like the transmission device 1a, includes an FPGA 10b, a memory 12b, an SFP 20b, optical amplifiers 30b and 31b, VOAs 21b and 32b, optical splitters 22b and 23b, filters 33b and 34b, and a PD 24b. , 25b.

The optical amplifiers 30a and 30b respectively amplify main signal lights Sm and Sm' input from adjacent nodes. FPGAs 10a and 10b control gains of optical amplifiers 30a and 30b, respectively. The main signal light Sm is input from the optical amplifier 30a to the VOA 32a, and the main signal light Sm' is input from the optical amplifier 30b to the VOA 32b. The VOAs 32a, 32b attenuate the main signal lights Sm, Sm', respectively. FPGAs 10a and 10b control the attenuation of VOAs 32a and 32b, respectively. The main signal light Sm is input from the VOA 32a to the filter 33a, and the main signal light Sm' is input from the VOA 32b to the filter 33b.

The SFPs 20a and 20b are optical modules detachable from the transmission devices 1a and 1b, respectively. The SFPs 20a and 20b transmit and receive supervisory signal lights Sc and Sc', respectively. In this example, the SFP 20a of the transmission device 1a is an example of an output unit, and outputs the supervisory signal light Sc. Also, the SFP 20b of the transmission device 1b is an example of a receiver, and receives the supervisory signal light Sc.

The supervisory signal light Sc is input from the SFP 20a to the VOA 21a. The VOA 21a is an example of an attenuator and attenuates the supervisory signal light Sc. The FPGA 10a is an example of a control section, and controls the attenuation of the VOA 21a. The supervisory signal light Sc is input from the VOA 21a to the filter 33a through the optical splitter 22a.

Also, the supervisory signal light Sc' is input from the SFP 20b to the VOA 21b. The VOA 21b attenuates the supervisory signal light Sc'. The FPGA 10b controls the attenuation of the VOA 21b. The supervisory signal light Sc' is input from the VOA 21b through the optical splitter 22b to the filter 33b.

The optical splitters 22a, 22b split the supervisory signal lights Sc, Sc' and guide them to filters 33a, 33b and PDs 24a, 24b. The PDs 24a and 24b detect the power of the supervisory signal lights Sc and Sc' by optical-electrical conversion. The FPGAs 10a and 10b monitor the transmission states of the supervisory signal lights Sc and Sc' based on the powers detected by the PDs 24a and 24b, for example.

The filter 33a is an example of a multiplexer, and multiplexes the supervisory signal light Sc with the main signal light Sm. The filter 33b multiplexes the supervisory signal light Sc' with the main signal light Sm'. Examples of the filters 33a and 33b include, but are not limited to, filters having a wavelength multiplexing function. The combined light of the supervisory signal light Sc and the main signal light Sm is output from the filter 33a to the transmission line 90, and the combined light of the supervisory signal light Sc' and the main signal light Sm' is output from the filter 33b to the transmission line 91.

The combined light of the supervisory signal light Sc and the main signal light Sm is input from the transmission line 90 to the filter 34b. The filter 34b is an example of a demultiplexing unit, and demultiplexes the main signal light Sm and the supervisory signal light Sc from the multiplexed light input from the transmission line 90. FIG.

Also, the combined light of the supervisory signal light Sc' and the main signal light Sm' is input from the transmission path 91 to the filter 34a. The filter 34a demultiplexes the combined light input from the transmission line 91 into the main signal light and the supervisory signal light Sc'.

Main signal lights Sm and Sm' are input from filters 34a and 34b to optical amplifiers 31a and 31b, respectively. The optical amplifiers 31a and 31b each amplify the main signal light Sm. FPGAs 10a and 10b control gains of optical amplifiers 31a and 31b, respectively. The main signal lights Sm and Sm' are output from the optical amplifiers 31a and 31b to adjacent nodes, respectively.

The supervisory signal light Sc is input from the filter 34b to the optical splitter 23b, and the supervisory signal light Sc' is input from the filter 34a to the optical splitter 23a. The optical splitter 23b splits the supervisory signal light Sc and guides it to the SFP 20b and the PD 25b, and the optical splitter 23a splits the supervisory signal light Sc' and guides it to the SFP 20a and the PD 25a.

The SFPs 20a and 20b receive the supervisory signal lights Sc and Sc' and output them to the FPGAs 10a and 10b, respectively. The FPGAs 10a and 10b extract supervisory control information from the payload data of the supervisory signal light Sc. The FPGA 10a controls the gains of the optical amplifiers 30a and 31a and the attenuation amounts of the VOAs 21a and 32a based on, for example, monitor control information. The FPGA 10b controls the gains of the optical amplifiers 30b and 31b and the attenuation amounts of the VOAs 21b and 32b, for example, based on the supervisory control information.

The PD 25b is an example of a first detector, and detects the power of the supervisory signal light Sc by optical-electrical conversion. Information on the power of the supervisory signal light Sc (hereinafter referred to as "power information") is input from the PD 25b to the FPGA 10b. The FPGA 10b inserts the power information into the payload data of the supervisory signal and outputs it to the SFPs 20a and 20b. Further, the PD 25a detects the power of the supervisory signal light Sc' by optical-electrical conversion, and notifies the FPGA 10a of the detected power.

The SFP 20b electro-optically converts the supervisory signal to generate and output supervisory signal light Sc'. As a result, the power information is sent from the transmission device 1b on the reception side that has received the optical supervisory signal Sc to the transmission device 1a on the transmission side that has transmitted the optical supervisory signal Sc. Note that the FPGA 10b of the transmission device 1b on the reception side is an example of a notification unit that notifies the transmission device 1a on the transmission side of the power of the supervisory signal light Sc detected by the PD 25b.

The SFP 20a of the transmission device 1a on the transmission side receives the supervisory signal light Sc' from the transmission device 1b on the reception side. The SFP 20a reproduces the supervisory signal by optical-electrical conversion of the supervisory signal light Sc' and outputs it to the FPGA 10a. The FPGA 10a extracts power information from the payload data of the supervisory signal.

The FPGA 10a controls the attenuation of the VOA 21a based on the power information. As a result, the supervisory signal light Sc is attenuated by the VOA 21a with an appropriate amount of attenuation.

The memories 12a and 12b store various parameters used for processing of the FPGAs 10a and 10b, respectively. The FPGAs 10a and 10b write information to memories 12a and 12b and read information from the memories 12a and 12b, respectively.

For example, the supervisory signal light Sc is transmitted along the route Rb from the transmission device 1a on the transmission side to the transmission device 1b on the reception side. The transmission device 1b on the reception side detects the power of the supervisory signal light Sc received from the transmission device 1a on the transmission side by the PD 25b, and notifies the transmission device 1a on the transmission side of the power information along the route Rc by means of the FPGA 10b. The transmission device 1a on the transmission side controls the attenuation amount of the VOA 21a using the FPGA 10a based on the notified power information. The operation of the transmission devices 1a and 1b in this case will be described below.

FIG. 2 is a flow chart showing an example of processing of the supervisory signal light Sc in the transmission device 1b on the receiving side. In FIG. 2, the process of step St2 and the processes of steps St3 and St4 are performed concurrently. Note that this process is repeatedly executed.

The filter 34b demultiplexes the main signal light Sm and the supervisory signal light Sc from the multiplexed light input via the transmission line 90 from the transmission device 1a on the transmission side (step St1). The SFP 20b receives the demultiplexed supervisory signal light Sc (step St2). The main signal light Sm is input to the optical amplifier 31b and amplified.

The PD 25b also detects the power of the demultiplexed supervisory signal light Sc (step St3). Next, the FPGA 10b inserts the power information into the payload data of the supervisory signal light Sc' in the opposite direction and notifies it to the transmission device 1a on the transmission side (step St4). In this manner, the transmission device 1b on the receiving side processes the supervisory signal light Sc and the main signal light Sm.

FIG. 3 is a flow chart showing an example of transmission processing of the supervisory signal light Sc in the transmission device 1a on the transmission side. Note that this process is repeatedly executed.

The SFP 20a of the transmission device 1a on the transmission side outputs the supervisory signal light Sc (step St11). Next, the VOA 21a attenuates the supervisory signal light Sc by the amount of attenuation set by the FPGA 10a (step St12).

Next, the filter 33a multiplexes the main signal light Sm and the supervisory signal light Sc (step St13). At this time, the multiplexed light is output to the transmission line 90 . In this manner, the transmission device 1a on the transmission side executes the transmission processing of the supervisory signal light Sc.

FIG. 4 is a flowchart showing an example of attenuation control processing in the transmission device 1a on the transmission side. Prior to this process, the attenuation amount of the VOA 21a is set to the lower limit.

In the transmission device 1a on the transmission side, the FPGA 10a acquires the power Pc of the supervisory signal light Sc detected by the PD 25b of the transmission device 1b on the reception side as power information from the payload data of the supervisory signal light Sc' received by the SFP 20a. (Step St21).

Next, the FPGA 10a compares the difference between the current attenuation amount of the VOA 21a and the upper limit value Am of the attenuation amount of the VOA 21a with the threshold value THa (step St22). Here, the upper limit value Am is determined according to the attenuation performance of the VOA 21a of the transmission device 1a. Further, the current attenuation amount is stored in the memory 12a, for example.

When the difference between the attenuation amount and the upper limit value Am is equal to or less than the threshold value THa (Yes in step St22), the FPGA 10a determines that the attenuation amount of the VOA 21a of the transmission device 1a cannot be made larger than the current set value, and performs control processing. exit. Note that the threshold THa is an example of a second threshold, and is a sufficiently small value so that the attenuation amount can be considered substantially equal to the upper limit value Am.

If the difference between the attenuation amount and the upper limit value Am is greater than the threshold value THa (No in step St22), the FPGA 10a sets the difference between the power Pc of the supervisory signal light Sc and the minimum received power Pco of the SFP 20b of the transmission device 1b on the receiving side to the threshold value THc. (step St23). The minimum received power Pco is an example of a target value for the power Pc of the supervisory signal light Sc.

When the difference between the power Pc and the minimum received power Pco is equal to or less than the threshold THc (Yes in step St23), the FPGA 10a determines that the power Pc is substantially equal to the minimum received power Pco, and terminates the control process. Note that the threshold THc is an example of a first threshold, and is a sufficiently small value so that the power Pc can be considered substantially equal to the minimum received power Pco.

If the difference between the power Pc and the minimum received power Pco is greater than the threshold THc (No in step St23), the FPGA 10a adds ΔA to the attenuation of the VOA 21a (step St24). At this time, the FPGA 10a sets the attenuation amount increased by ΔA to the VOA 21a. Therefore, the power (transmission power) of the supervisory signal light Sc transmitted from the transmission device 1a on the transmission side decreases in accordance with the increment ΔA of the attenuation amount.

After that, each process after step St21 is executed again. As a result, the attenuation amount increases by ΔA each time the process of step St24 is executed, so the power of the supervisory signal light Sc gradually decreases and approaches the target value of the minimum received power Pco. In this manner, the attenuation control process is executed.

In this way, the FPGA 10a of the transmission device 1a on the transmission side adjusts the attenuation of the VOA 21a so that the power Pc of the supervisory signal light Sc notified from the FPGA 10b of the transmission device 1b on the reception side approaches the predetermined minimum received power Pco. Control. For this reason, the transmission apparatus 1a sets the minimum received power Pco to a sufficiently small value within a range that satisfies the transmission quality requirements of the supervisory signal light Sc, thereby suppressing the nonlinear optical effect without degrading the supervisory control function. can be suppressed.

The minimum received power Pco is set to the minimum power of light that can be received by the SFP 20b, for example. Therefore, since the transmission device 1a can reduce the power Pc of the supervisory signal light Sc received by the SFP 20b of the transmission device 1b on the receiving side to the limit, the nonlinear optical effect can be suppressed more effectively.

The minimum received power Pco is set to the minimum value of light power that can be received within the specification of the light receiving characteristics of the SFP 20b, for example. This minimum value is, for example, the minimum reception sensitivity defined in the specifications of the light receiving characteristics of the SFP 20b. The minimum reception sensitivity is the minimum value of reception power required to achieve the transmission quality required for the transmission system, and is one of the parameters that indicate the reception performance of the SFP 20b in the market for each product model number.

An example of the index value of transmission quality is the bit error rate, and the minimum reception sensitivity is, for example, the amount of reception power that satisfies the condition that the bit error rate of supervisory signal light Sc is equal to or less than a specified value required for the transmission system. Specified as a minimum value.

Therefore, the transmission device 1b can more reliably guarantee the transmission quality of the supervisory signal light Sc based on the specifications of the light receiving characteristics of the SFP 20b by controlling the attenuation of the VOA 21a with the minimum light receiving sensitivity as a target value. Note that the minimum received power Pco is stored in advance in the memory 12a.

In addition, the FPGA 10a sets the difference between the power Pc of the supervisory signal light Sc and the minimum received power Pco of the SFP 20b of the transmission device 1b on the receiving side to be equal to or less than the threshold THc, or the difference between the attenuation amount of the VOA 21a and the upper limit Am to the threshold THa. Attenuation control is stopped if:

Therefore, the FPGA 10a can stop controlling the attenuation amount when the attenuation amount reaches the upper limit value Am before the power Pc of the supervisory signal light Sc reaches the minimum received power Pco. Therefore, the FPGA 10a does not erroneously set an attenuation amount exceeding the upper limit value Am to the VOA 21a.

Also, the VOA 21a attenuates the supervisory signal light Sc input to the filter 33a. Therefore, the VOA 21a attenuates only the supervisory signal light Sc out of the supervisory signal light Sc and the main signal light Sm. Therefore, the influence of the attenuation of the supervisory signal light Sc on the power of the main signal light Sm is suppressed.

(Second embodiment)
The VOA 21a attenuates only the supervisory signal light Sc as described above, but may attenuate the supervisory signal light Sc and the main signal light Sm as follows.

FIG. 5 is a block diagram showing the transmission system of the second embodiment. In FIG. 5, the same reference numerals are assigned to the same components as in FIG. 1, and the description thereof will be omitted.

The transmission device 1a has a VOA 26a between the filter 33a and the transmission line 90 instead of the VOA 21a and the VOA 32a of the first embodiment. Further, the transmission device 1b has a VOA 26b between the filter 33b and the transmission line 91 instead of the VOA 21b and the VOA 32b of the first embodiment. The VOA 26a attenuates the supervisory signal light Sc and the main signal light Sm output from the filter 33a. The VOA 26b attenuates the supervisory signal light Sc' and the main signal light Sm' output from the filter 33b. Note that the VOA 26a is an example of an attenuation section.

Since the transmission apparatus 1a attenuates the supervisory signal light Sc and the main signal light Sm by one VOA 26a, it does not require two VOAs 21a and 32a as in the first embodiment. Therefore, the cost and scale of the transmission device 1a are reduced. Since the transmission device 1b also attenuates the supervisory signal light Sc' and the main signal light Sm' by one VOA 26b, the cost and scale are reduced.

The transmission device 1b also has an optical splitter 35b and a PD 27b for detecting the power of the main signal light Sm input from the transmission line 90. FIG. The optical splitter 35b is provided between the filter 34b and the optical amplifier 31b. The optical splitter 35b splits the main signal light Sm and guides it to the optical amplifier 31a and the PD 27b.

The PD 27b detects the power of the main signal light Sm by optical-electrical conversion of the main signal light Sm. Information on the power of the main signal light Sm (power information) is notified from the PD 25b to the FPGA 10b. In addition, PD27b is an example of a 2nd detection part.

The FPGA 10b inserts the respective power information of the supervisory signal light Sc and the main signal light Sm into the payload data of the supervisory signal light Sc' in the opposite direction, and outputs the payload data to the SFP 20b. As a result, the powers of the supervisory signal light Sc and the main signal light Sm are notified from the transmission device 1b on the reception side to the transmission device 1a on the transmission side along the route Rc.

Further, the transmission device 1a has an optical splitter 35a and a PD 27a for detecting the power of the main signal light Sm' inputted from the transmission line 91, like the transmission device 1b. The PD 27a detects the power of the main signal light Sm' split by the optical splitter 35a and notifies it to the FPGA 10a.

The FPGA 10a of the transmission device 1a on the transmission side controls the attenuation amount of the VOA 26a so that the power of the main signal light Sm does not fall below the lower limit in the above control processing.

FIG. 6 is a flow chart showing an example of processing of the supervisory signal light Sc and the main signal light Sm in the transmission device 1b on the receiving side. In FIG. 6, the same reference numerals are assigned to the same processes as in FIG. 2, and the description thereof will be omitted. In FIG. 6, the process of step St2, the processes of steps St3 and St4, and the processes of steps St5 and St6 are performed in parallel. Note that this process is repeatedly executed.

After the filter 34b demultiplexes the main signal light Sm and the supervisory signal light Sc (step St1), the PD 27b detects the power of the main signal light Sm (step St5). Next, the FPGA 10b notifies the transmission device 1a on the transmission side of the power information of the main signal light Sm (step St6). In this manner, the transmission device 1b on the receiving side processes the supervisory signal light Sc and the main signal light Sm.

FIG. 7 is a flowchart showing an example of transmission processing of the supervisory signal light Sc and the main signal light Sm in the transmission device 1a on the transmission side. Note that this process is repeatedly executed.

After outputting the supervisory signal light Sc (step St11), the filter 33a multiplexes the supervisory signal light Sc and the main signal light Sm (step St12a). Next, the VOA 26a attenuates the supervisory signal light Sc and the main signal light Sm by the attenuation amount set by the FPGA 10a (step St13a). Therefore, the attenuation amounts of the supervisory signal light Sc and the main signal light Sm are the same. In this manner, the transmission device 1a on the transmission side executes transmission processing of the supervisory signal light Sc and the main signal light Sm.

FIG. 8 is a flow chart showing another example of the attenuation amount control processing in the transmission device 1a on the transmission side. In FIG. 8, the same reference numerals are given to the same components as in FIG. 4, and the description thereof will be omitted. Prior to this process, the attenuation amount of the VOA 26a is set to the lower limit.

After obtaining the power Pc of the supervisory signal light Sc (step St21), the FPGA 10a obtains the power Ps of the main signal light Sm indicated by the power information (step St21a). Note that the process of step St21a may be executed prior to the process of step St21.

Next, the FPGA 10a performs determination processing of step St22 for the current attenuation amount of the VOA 26a. If the difference between the upper limit value Am and the attenuation amount is equal to or less than the threshold value THa (Yes in step St22), the FPGA 10a ends the process.

When the difference between the upper limit value Am and the attenuation amount is greater than the threshold value THa (No in step St22), the FPGA 10a compares the difference between the power Ps of the main signal light Sm and its lower limit value Pso with the threshold value THs (step St22a). . The lower limit value Pso is, for example, the minimum value of power required to transmit the main signal light Sm to the adjacent node, and is determined by conditions such as the distance of the transmission path to the adjacent node.

When the difference between the power Ps and the lower limit value Pso is equal to or less than the threshold value THs (Yes in step St22a), the FPGA 10a ends the control process so that the power Ps does not become smaller than the current value and the transmission quality does not deteriorate. Note that the threshold THs is an example of a third threshold, and is a sufficiently small value so that the power Ps can be considered substantially equal to the lower limit value Pso.

When the difference between the power Ps and the lower limit value Pso is greater than the threshold THs (No in step St22a), the FPGA 10a executes the determination process in step St23. Also, the FPGA 10a adds ΔA to the attenuation amount of the VOA 26a (step St24). At this time, the FPGA 10a sets the attenuation amount increased by ΔA to the VOA 26a. Therefore, the powers of the supervisory signal light Sc and the main signal light Sm transmitted from the transmission device 1a on the transmitting side decrease according to the increment ΔA of the attenuation amount. In this manner, the attenuation control process is executed.

In this way, when the difference between the power Pc of the supervisory signal light Sc and the minimum received power Pco of the SFP 20b of the transmission device 1b on the receiving side is equal to or less than the threshold THc, the FPGA 10a sets the difference between the attenuation amount of the VOA 26a and the upper limit Am to the threshold. If it is equal to or less than THa, or if the difference between the power Ps of the main signal light Sm and the lower limit value Pso is equal to or less than the threshold THs, control of the attenuation amount is stopped.

Therefore, the FPGA 10a can stop controlling the attenuation amount when the attenuation amount reaches the upper limit value Am before the power Pc of the supervisory signal light Sc reaches the minimum received power Pco. Further, the FPGA 10a can stop the attenuation amount control when the power Ps of the main signal light Sm reaches the lower limit value Pso before the power Pc of the supervisory signal light Sc reaches the minimum received power Pco. Therefore, the deterioration of transmission quality due to the power Ps of the main signal light Sm falling below the lower limit Pso is suppressed.

In each of the above-described embodiments, the power information of the main signal light Sm or the supervisory signal light Sc is sent from the transmission device 1b on the reception side to the transmission device 1a on the transmission side over the route Rc via the transmission line 91. , but not limited to. The FPGA 10b of the transmission device 1b on the reception side notifies power information to the transmission device 1a on the transmission side via, for example, a NE-OpS (Network Element Operation System) (not shown) that controls the transmission devices 1a and 1b. good too.

Further, although the attenuation amounts of the VOAs 21a and 26a are controlled by the FPGA 10a in each of the above-described embodiments, the present invention is not limited to this. For example, the attenuation may be controlled by a processor such as a CPU (Central Processing Unit) operating according to software.

In each of the above-described embodiments, an example was given in which the transmission device 1a was on the transmission side and the transmission device 1b was on the reception side. The power of the supervisory signal light Sc' can be appropriately controlled by the same processing.

The embodiments described above are examples of preferred implementations of the present invention. However, the present invention is not limited to this, and various modifications can be made without departing from the scope of the present invention.

Note that the following notes are further disclosed with respect to the above description.
(Appendix 1) a first transmission device that transmits main signal light to a transmission line;
a second transmission device that receives the main signal light from the first transmission device via the transmission line,
The first transmission device,
an output unit that outputs supervisory signal light containing information on supervisory control of the first transmission device and the second transmission device;
an attenuation unit that attenuates the supervisory signal light;
a multiplexing unit that multiplexes the supervisory signal light with the main signal light;
a control unit that controls the attenuation amount of the attenuation unit;
The second transmission device,
a demultiplexer for demultiplexing the main signal light and the supervisory signal light input from the transmission line;
a first detector that detects the power of the supervisory signal light;
a receiver that receives the supervisory signal light;
a notification unit that notifies the first transmission device of the power of the supervisory signal light detected by the first detection unit;
The transmission system according to claim 1, wherein the control section controls the attenuation amount of the attenuation section so that the power of the supervisory signal light notified from the notification section approaches a predetermined target value.
(Supplementary Note 2) The controller controls the amount of attenuation of the attenuator so that the power of the supervisory signal light notified from the notification unit approaches the minimum power of light that can be received by the receiver. The transmission system according to appendix 1, characterized in that it controls the
(Supplementary Note 3) The control unit causes the power of the supervisory signal light notified from the notification unit to approach the minimum power of light that can be received within the range of specifications of the light receiving characteristics of the reception unit. The transmission system according to appendix 1, wherein the attenuation amount of the attenuation unit is controlled as follows.
(Appendix 4) The transmission system according to any one of Appendices 1 to 3, wherein the attenuator attenuates the supervisory signal light input to the multiplexer.
(Additional Note 5) When the difference between the power of the supervisory signal light notified from the notification unit and the target value is equal to or less than a first threshold, or when the difference between the attenuation amount and the upper limit value of the attenuation amount is is equal to or less than a second threshold, the transmission system according to appendix 4, wherein control of the attenuation amount of the attenuation unit is stopped.
(Appendix 6) The transmission system according to any one of Appendices 1 to 3, wherein the attenuator attenuates the supervisory signal light and the main signal light output from the multiplexer.
(Appendix 7) The second transmission device has a second detection unit that detects the power of the main signal light,
the notification unit notifying the first transmission device of the power of the supervisory signal light detected by the first detection unit and the power of the main signal light detected by the second detection unit;
When the difference between the power of the supervisory signal light notified from the notification unit and the target value is equal to or less than a first threshold, the controller controls the difference between the attenuation amount and the upper limit value of the attenuation amount to be equal to or less than a second threshold. or if the difference between the power of the main signal light notified by the notification unit and the lower limit value of the power of the main signal light is equal to or less than a third threshold, the attenuation unit stops controlling the amount of attenuation. The transmission system according to appendix 6, characterized by:
(Appendix 8) In a transmission device that transmits main signal light to another transmission device via a transmission line,
an output unit for outputting supervisory signal light containing information on supervisory control of the transmission device and the other transmission device;
an attenuation unit that attenuates the supervisory signal light;
a multiplexing unit that multiplexes the supervisory signal light with the main signal light;
and a control section for controlling attenuation of the attenuator so that the power of the supervisory signal light received by the other transmission apparatus approaches a predetermined target value.
(Additional Note 9) The controller attenuates the attenuator so that the power of the supervisory signal light received by the other transmission device approaches the minimum power of light that can be received by the receiver. 9. Transmission device according to clause 8, characterized in that it controls the amount.
(Supplementary Note 10) The control unit controls the power of the supervisory signal light received by the other transmission device to be the minimum value of light power that can be received within the range of the specifications of the light receiving characteristics of the reception unit. The transmission device according to appendix 8, wherein the attenuation amount of the attenuator is controlled so as to be close to each other.
(Supplementary note 11) The transmission device according to any one of Supplementary notes 8 to 10, wherein the attenuator attenuates the supervisory signal light input to the multiplexer.
(Supplementary Note 12) The control unit, when the difference between the power of the supervisory signal light received by the other transmission device and the target value is equal to or less than a first threshold value, or the difference between the attenuation amount and the upper limit value of the attenuation amount 12. The transmission apparatus according to appendix 11, wherein control of the attenuation amount of the attenuation unit is stopped when the difference is equal to or less than a second threshold.
(Supplementary note 13) The transmission device according to any one of Supplementary notes 8 to 10, wherein the attenuator attenuates the supervisory signal light and the main signal light output from the multiplexer.
(Supplementary Note 14) When the difference between the power of the supervisory signal light received by the other transmission device and the target value is equal to or less than a first threshold, the controller controls the difference between the attenuation amount and the upper limit value of the attenuation amount. is equal to or less than a second threshold, or the difference between the power of the main signal light received by the other transmission device and the lower limit of the power of the main signal light is equal to or less than a third threshold, the attenuation of the attenuator 14. Transmission device according to clause 13, characterized in that it stops controlling the quantity.
(Appendix 15) In the transmission method for transmitting the main signal light from the first transmission device to the second transmission device via the transmission line,
The first transmission device,
outputting supervisory signal light containing information on supervisory control of the first transmission device and the second transmission device;
Attenuating the supervisory signal light by an attenuator,
combining the supervisory signal light with the main signal light;
The second transmission device,
demultiplexing the main signal light and the supervisory signal light input from the transmission line;
detecting the power of the supervisory signal light by a first detector;
receiving the supervisory signal light by a receiving unit;
notifying the first transmission device of the power of the supervisory signal light detected by the first detection unit;
The transmission method, wherein the first transmission device controls the attenuation of the attenuator so that the power of the supervisory signal light notified from the second transmission device approaches a predetermined target value.
(Supplementary Note 16) The attenuation amount of the attenuator is controlled so that the power of the supervisory signal light notified from the second transmission device approaches the minimum power of light that can be received by the receiver. The transmission method according to appendix 15, characterized by:
(Supplementary Note 17) The power of the supervisory signal light notified from the second transmission device approaches the minimum value of the power of light that can be received within the specification of the light receiving characteristics of the receiver. 16. The transmission method according to appendix 15, wherein the attenuation amount of the attenuation unit is controlled.
(Supplementary note 18) The transmission method according to any one of Supplementary notes 15 to 17, wherein the attenuator attenuates the supervisory signal light combined with the main signal light.
(Supplementary Note 19) When the difference between the power of the supervisory signal light notified from the second transmission device and the target value is equal to or less than a first threshold, or the difference between the attenuation amount and the upper limit value of the attenuation amount is a second 19. The transmission method according to appendix 18, wherein control of the attenuation amount of the attenuator is stopped when it is equal to or less than the threshold.
(Supplementary note 20) The transmission method according to any one of Supplementary notes 15 to 17, wherein the attenuator attenuates the multiplexed supervisory signal light and main signal light.

1a, 1b transmission device 10a, 10b FPGA
20a, 20b SFPs
21a, 21b, 26a, 26b VOAs
25a, 25b PDs
33a, 33b, 34a, 34b Filter 90, 91 Transmission line

Claims (7)

a first transmission device that transmits main signal light to a transmission line;
a second transmission device that receives the main signal light from the first transmission device via the transmission line,
The first transmission device,
an output unit that outputs supervisory signal light containing information on supervisory control of the first transmission device and the second transmission device;
an attenuation unit that attenuates the supervisory signal light;
a multiplexing unit that multiplexes the supervisory signal light with the main signal light;
a control unit that controls the attenuation amount of the attenuation unit;
The second transmission device,
a demultiplexer that demultiplexes the main signal light and the supervisory signal light input from the transmission line;
a first detector that detects the power of the supervisory signal light;
a receiver that receives the supervisory signal light;
a notification unit that notifies the first transmission device of the power of the supervisory signal light detected by the first detection unit;
When the difference between the power of the supervisory signal light notified from the notification unit and the minimum light receiving sensitivity defined in the specifications of the light reception characteristics of the reception unit is greater than a first threshold, the control unit By controlling the attenuation amount of the attenuator so that the power of the notified supervisory signal light approaches the minimum light receiving sensitivity, the power of the supervisory signal light is reduced, and the first transmission device and the second transmission are controlled. A transmission system characterized by suppressing a nonlinear optical effect of said main signal light and said supervisory signal light in said transmission path without degrading the supervisory control function of an apparatus. 2. The transmission system according to claim 1, wherein the attenuator attenuates the supervisory signal light input to the multiplexer. When the difference between the power of the supervisory signal light notified from the notification unit and the minimum light-receiving sensitivity is equal to or less than the first threshold value, or the difference between the attenuation amount and the upper limit value of the attenuation amount 3. The transmission system according to claim 2, wherein control of the attenuation amount of said attenuation unit is stopped when is equal to or less than a second threshold. 2. The transmission system according to claim 1, wherein the attenuator attenuates the supervisory signal light and the main signal light output from the multiplexer. The second transmission device has a second detection unit that detects power of the main signal light,
the notification unit notifying the first transmission device of the power of the supervisory signal light detected by the first detection unit and the power of the main signal light detected by the second detection unit;
When the difference between the power of the supervisory signal light notified from the notification unit and the minimum light-receiving sensitivity is equal to or less than the first threshold value, the control unit determines that the difference between the attenuation amount and the upper limit value of the attenuation amount is When the difference between the power of the main signal light and the lower limit value of the power of the main signal light notified by the notification unit is equal to or less than the third threshold, the attenuation amount of the attenuation unit 5. Transmission system according to claim 4, characterized in that the control is stopped. In a transmission device that transmits main signal light to another transmission device via a transmission line,
an output unit for outputting supervisory signal light containing information on supervisory control of the transmission device and the other transmission device;
an attenuation unit that attenuates the supervisory signal light;
a multiplexing unit that multiplexes the supervisory signal light with the main signal light;
When the difference between the power of the supervisory signal light received by the receiving unit of the other transmission device and the minimum light receiving sensitivity defined in the specifications of the light receiving characteristics of the receiving unit is greater than a first threshold, the receiving unit receives by controlling the attenuation amount of the attenuator so that the power of the received supervisory signal light approaches the minimum light receiving sensitivity, the power of the supervisory signal light is reduced, and the supervisory control of the transmission device and the other transmission devices and a controller for suppressing a nonlinear optical effect of the main signal light and the supervisory signal light in the transmission path without lowering the function. In a transmission method for transmitting main signal light from a first transmission device to a second transmission device via a transmission line,
The first transmission device,
outputting supervisory signal light containing information on supervisory control of the first transmission device and the second transmission device;
Attenuating the supervisory signal light by an attenuator,
combining the supervisory signal light with the main signal light;
The second transmission device,
demultiplexing the main signal light and the supervisory signal light input from the transmission line;
detecting the power of the supervisory signal light by a first detector;
receiving the supervisory signal light by a receiving unit;
notifying the first transmission device of the power of the supervisory signal light detected by the first detection unit;
When the difference between the power of the supervisory signal light notified from the second transmission device and the minimum light receiving sensitivity defined in the specifications of the light receiving characteristics of the receiving unit is greater than a first threshold, By controlling the attenuation amount of the attenuator so that the power of the supervisory signal light notified from the second transmission device approaches the minimum light receiving sensitivity, the power of the supervisory signal light is reduced and the first transmission is performed. A transmission method characterized by suppressing a nonlinear optical effect of said main signal light and said supervisory signal light in said transmission line without deteriorating supervisory control functions of said apparatus and said second transmission apparatus.

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